Equivalents Of Methanol Research Articles

Novel dragon fruit peel ash-derived solid catalyst for biodiesel production and PET waste recycling

The present protocol demonstrates the development of an affordable methodology for synthesizing biodiesel and depolymerizing PET waste using dragon fruit (Hylocereus costaricensis or Hylocereus polyrhizus) peel ash derived solid catalyst. The reported catalytic process yielded 99 % biodiesel at room temperature in 5 h with 8 wt% catalyst amounts and 12 M equivalents of methanol, while requiring just 20 min of run time at an elevated temperature (65 °C). The reaction was found to be endothermic pseudo-first order reaction having activation energy of 56.36 kJ mol−1. Meanwhile, PET waste was depolymerized to bis(2-hydroxyethyl) terephthalate (BHET) in 1.5 h at 190 °C with 16 equivalents of ethylene glycol and 4 wt% of the catalyst, giving 84 % of the desired monomer. The developed catalyst and the resultant products are thoroughly characterized using a variety of techniques to determine the catalyst's chemical composition and to confirm the formation of the desired products.

Chiral Sulfide/Phosphoric Acid Cocatalyzed Enantioselective Intermolecular Oxysulfenylation of Alkenes with Phenol and Alcohol O -Nucleophiles

Chiral Sulfide/Phosphoric Acid Cocatalyzed Enantioselective Intermolecular Oxysulfenylation of Alkenes with Phenol and Alcohol <i>O</i> -Nucleophiles

Synthesis, Structure and Reactivity of a Cyapho-Cyanamide Salt.

We describe a facile synthesis of the cyapho-cyanamide salt [Na(18-crown-6)][N(CN)(CP)] from reaction of [Na(18-crown-6)][PH2 ] (18-crown-6=1,4,7,10,13,16-hexaoxacyclooctadecane) with dimethyl N-cyanocarbonimidate, (MeO)2 C=N(CN). The reaction proceeds with elimination of two equivalents of methanol. Careful tuning of the reaction conditions allowed for the isolation and characterization of the N-cyano(carboximidate)phosphide intermediate [HP{C(OMe)N(CN)}]- . Due to the adverse effects of methanol in these reaction mixtures, a bulk scale synthesis of [Na(18-crown-6)][N(CN)(CP)] could be achieved by addition of a base (LiHMDS) to neutralize the resulting alcohol. Further reactivity studies of this anion reveal that functionalization at the phosphorus atom is viable to yield a new family of cyanide-functionalised phosphorus heterocycles.

Synthesis, Structure and Reactivity of a Cyapho‐Cyanamide Salt

AbstractWe describe a facile synthesis of the cyapho‐cyanamide salt [Na(18‐crown‐6)][N(CN)(CP)] from reaction of [Na(18‐crown‐6)][PH2] (18‐crown‐6=1,4,7,10,13,16‐hexaoxacyclooctadecane) with dimethyl N‐cyanocarbonimidate, (MeO)2C=N(CN). The reaction proceeds with elimination of two equivalents of methanol. Careful tuning of the reaction conditions allowed for the isolation and characterization of the N‐cyano(carboximidate)phosphide intermediate [HP{C(OMe)N(CN)}]−. Due to the adverse effects of methanol in these reaction mixtures, a bulk scale synthesis of [Na(18‐crown‐6)][N(CN)(CP)] could be achieved by addition of a base (LiHMDS) to neutralize the resulting alcohol. Further reactivity studies of this anion reveal that functionalization at the phosphorus atom is viable to yield a new family of cyanide‐functionalised phosphorus heterocycles.

Complete Enzymatic Oxidation of Methanol to Carbon Dioxide: Towards More Eco‐Efficient Regeneration Systems for Reduced Nicotinamide Cofactors

AbstractA novel system for in situ regeneration of reduced nicotinamide cofactors (NADH) is proposed: through a cascade of alcohol dehydrogenase (ADH), formaldehyde dismutase (FDM) and formate dehydrogenase (FDH) complete oxidation of methanol to carbon dioxide (CO2) is coupled to the regeneration of NADH. As a consequence, from one equivalent of methanol three equivalents of NADH can be obtained. The feasibility of this cascade is demonstrated at the examples of an NADH‐dependent reduction of conjugated CC‐double bonds (catalysed by an enoate reductase) and the NADH‐dependent hydroxylation of phenols (catalysed by a monooxygenase). The major limitation of the current regeneration system is the comparably poor catalytic efficiency of the methanol oxidation step (low kcat and high KM value of the ADH used) necessitating higher than theoretical methanol concentrations.magnified image

Enantioselective addition of dialkylzinc to aromatic aldimines mediated by camphor-derived chiral β-amino alcohols.

The enantioselective addition of diethylzinc or dimethylzinc to N-(diphenylphosphinoyl)imines mediated by 1 or 2 could be achieved in high yields (70-97 %) and enantioselectivities (85-98 % ee). The catalytic loading of 1 or 2 a could be reduced to 10 mol % for methylation or ethylation of imines in high yields and enantioselectivities (79-96 %) when the reaction was conducted in the presence of 1.8 equiv of methanol. N-Monosubstituted amino alcohols induced higher enantioselectivity than their N,N-disubstituted congener in our catalytic system.

Plasma, blood and liver tissue sample preparation methods for the separate quantification of liposomal-encapsulated prednisolone phosphate and non-encapsulated prednisolone

Besides the development of sample preparation methods for the determination of separate liposomal-encapsulated prednisolone phosphate and non-encapsulated prednisolone concentrations in murine plasma and blood, this article also presents the first description of an accurate sample preparation method for the determination of such separate concentrations in the murine liver. The quantitative differentiation is based on the immediate hydrolysis of prednisolone phosphate (PP) into prednisolone (P) after its release from the liposomes in vivo: PP represents the encapsulated drug, while P represents the non-encapsulated drug. The use of 10 ml methanol/g tissue during homogenization of liver tissue ensures complete liposome rupture, prevention of the dephosphorylation of PP released during homogenization, sufficient clean supernatants, excellent extraction of P and sufficient extraction of PP and excellent accuracies and precision complying with the internal guidelines for pre-clinical studies (80–120% and maximal 20%, respectively). Similarly, the matching sample preparation methods for plasma and blood involve protein precipitation with four equivalents of methanol also ensuring accuracies and precision complying with the internal guidelines for pre-clinical studies. Application of these sample preparation methods is going to generate the first pharmacokinetic (PK) profile of a liposomal preparation, in which the encapsulated and non-encapsulated drug concentrations in a tissue are measured separately. Such separated concentration profiles can gain important insights into the PKs of liposomal PP and probably also with regard to liposomal formulations in general, like the quantification of the in vivo drug release from the liposomes.

The Enzymatic Production of Biodiesel from Pomace Oil Using Immobilized Thermomyces lanuginosus

In the present work, microbial lipase from Thermomyces lanuginosus was immobilized by covalent binding onto styrene-divinylbenzene polyglutaraldehyde copolymer. Immobilized support material was used to produce biodiesel with pomace oil and methanol. The properties of the support and immobilized derivative were evaluated by scanning electron microscopy. Biodiesel production was carried out with a semi-continuous operation system. Methanol was added into the reactor by three successive additions of 1:6 molar equivalent of methanol to avoid enzyme inhibition. The maximum methyl esters yield was obtained as 98%.

Production of biodiesel from plant oil hydrolysates using an Aspergillus oryzae whole-cell biocatalyst highly expressing Candida antarctica lipase B

For enzymatic biodiesel production from plant oil hydrolysates, an Aspergillus oryzae whole-cell biocatalyst that expresses Candida antarctica lipase B (r-CALB) with high esterification activity was developed. Each of soybean and palm oils was hydrolyzed using Candida rugosa lipase, and the resultant hydrolysates were subjected to esterification where immobilized r-CALB was used as a catalyst. In esterification, r-CALB afforded a methyl ester content of more than 90% after 6h with the addition of 1.5M equivalents of methanol. Favorably, stepwise additions of methanol and a little water were unnecessary for maintaining the lipase stability of r-CALB during esterification. During long-term esterification in a rotator, r-CALB can be recycled for 20 cycles without a significant loss of lipase activity, resulting in a methyl ester content of more than 90% even after the 20th batch. Therefore, the presented reaction system using r-CALB shows promise for biodiesel production from plant oil hydrolysates.

A General Procedure for the Synthesis of Enones via Gold-Catalyzed Meyer−Schuster Rearrangement of Propargylic Alcohols at Room Temperature

Meyer-Schuster rearrangements of propargylic alcohols take place readily at room temperature in toluene with 1-2 mol % PPh(3)AuNTf(2), in the presence of 0.2 equiv of 4-methoxyphenylboronic acid or 1 equiv of methanol. Good to excellent yields of enones can be obtained from secondary and tertiary alcohols, with high selectivity for the E-alkene in most cases. A one-pot procedure for the conversion of primary propargylic alcohols into β-arylketones was also developed, via Meyer-Schuster rearrangement followed by Pd-catalayzed addition of a boronic acid.

Living Ring-Opening Homo- and Copolymerization of ε-Caprolactone and l- and d,l-Lactides by Dimethyl(salicylaldiminato)aluminum Compounds

The dimethylaluminum compounds {3-tBu-2-(O)C6H3CH═N−R}AlMe2 [R = C6H5 (1); 2,6-iPr2C6H3 (2); C6F5 (3)] were used as initiators in the ring-opening polymerization (ROP) of ε-caprolactone, l-lactide, and d,l-lactide. Compound 3, in combination with 1 equiv of methanol, exhibited a living behavior in the ROP of the cyclic esters. Such a feature allowed the preparation of poly(d,l-lactide-block-ε-caprolactone) and poly(l-lactide-block-ε-caprolactone) copolymers. Random copolymers of ε-caprolactone and l-lactide and of ε-caprolactone and d,l-lactide were also synthesized by compound 3. NMR and DSC characterization confirmed a highly random structure of these copolymers, even in the absence of transesterification reactions. All the materials, characterized by GPC, showed high molecular weight and narrow molecular weight distributions.

Electrochemical and Electronic Structure Investigations of the [S3N3]•Radical and Kinetic Modeling of the [S4N4]n/[S3N3]n(n= 0, −1) Interconversion

Voltammetric studies of S(4)N(4) employing both cyclic (CV) and rotating disk (RDE) methods in CH(2)Cl(2) at a glassy carbon electrode reveal a one-electron reduction at -1.00 V (versus ferrocene/ferrocenium), which produces a second redox couple at -0.33 V, confirmed to be the electrochemically generated [S(3)N(3)](-) by CV studies on its salts. Diffusion coefficients (CH(2)Cl(2)/0.4 M [(n)Bu(4)N][PF(6)]) estimated by RDE methods: S(4)N(4), 1.17 x 10(-5) cm(2) s(-1); [S(3)N(3)](-), 4.00 x 10(-6) cm(2) s(-1). Digital simulations of the CVs detected slow rates of electron transfer for both couples and allowed for a determination of rate constants for homogeneous chemical reaction steps subsequent to electron transfer. The common parameters (k(f1) = 2.0 +/- 0.5 s(-1), k(s1) = 0.034 +/- 0.004 cm s(-1) for [S(4)N(4)](-/0); k(f2) = 0.4 +/- 0.2 s(-1), k(s2) = 0.022 +/- 0.005 cm s(-1) for [S(3)N(3)](-/0) at T = 21 +/- 2 degrees C) fit well to a "square-scheme" mechanism over the entire range of data with first order decay of both redox products. An alternate model could also be fit wherein [NS](*) liberated in the first step reacts with formed [S(3)N(3)](*) to reproduce S(4)N(4) with an apparent second order rate constant k(f2)' = 1.1 +/- 0.3 x 10(3) M(-1) s(-1). The crystal structure of [PPN][S(3)N(3)] was determined by X-ray crystallography indicating the solvation of the anion by 1 equiv of methanol. The generated [S(4)N(4)](-*) radical anion was detected by the Simultaneous Electrochemical Electron Paramagnetic Resonance (SEEPR) method to give: (a) [(32)S(4)(14)N(4)](-*), 9 lines, a((14)N) = 0.118 mT; (b) [(32)S(4)(15)N(4)](-*), 5 lines, a((15)N) = 0.164 mT; (c) [(33)S(4)(14)N(4)](-*), estimated a((14)N) = 0.118, a((33)S = 0.2 mT); g = 2.0008(1). Equivalence of (33)S hyperfine splittings is consistent with dynamic averaging of the C(2v) geometry in solution. High-level electronic structure calculations provide evidence for an open-shell doublet triradicaloid character to the ground state wave function of [S(3)N(3)](*).

Recent developments in the chiral synthesis of homoallylic amines via organoboranes

Abstract Among the plethora of protocols for the preparation of chiral homoallylic amines, the use of boron-based reagents remains relatively undeveloped. However, the recent advances in the use of α-pinene-based versatile reagents for the synthesis of such amines confirmed that very high enantioselectivity and outstanding diastereoselectivity can be readily achieved. Addition of the "allyl"boron reagents to various N-substituted imines provided the desired amine products in high yields and high to very high ee. The discovery that an addition of 1.0 equiv of methanol or water to the "allyl"boration reaction with N-masked imines is critical allowed for higher yields and noticeably improved ee. The use of N-aluminoimines, which are not only easy to prepare by a partial reduction of nitriles, but are also relatively stable for both enolizable and non-enolizable substrates, considerably expanded the scope of the reactions. In this review, the developments in the syntheses of chiral homoallylic amines using organoboranes, with the particular accent on the reagent-controlled reactions, are summarized. Additionally, the novel methodology for the crotyl- and alkoxyallylboration of imines using trialkylboron "ate" complexes is described.

Lipase-catalyzed methanolysis of palm oil in presence and absence of organic solvent for production of biodiesel

Enzymatic production of methyl esters (biodiesel) by methanolysis of palm oil in presence and absence of organic solvent was investigated using Candida antarctica lipase immobilized on acrylic resin as a biocatalyst. Although, at least molar equivalent of methanol (methanol–palm oil ratio 3:1) is required for the complete conversion of palm oil to methyl esters, lipase catalyzed methanolysis of palm oil in absence of organic solvent was poisoned by adding more than 1/3 molar equivalent of methanol. The use of polar organic solvents prevented the lipase to be poisoned in methanolysis with a molar equivalent of methanol, and tetrahydrofuran (THF) was found to be the most effective. The presence of water in methanolysis of palm oil both in presence and absence of THF inhibited the reaction rate but this inhibition was considerably low in THF containing system. The palm oil-lipase (w/w) ratio significantly influenced the activity of lipase and the optimal ratio in presence and absence of THF was 100 and 50, respectively.

Enantioselective Addition of Diethylzinc to N‐Diphenylphosphinoylimines Employing Cinchonidine and Cinchonine as Chiral Ligands.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Enantioselective addition of diethylzinc to N-diphenylphosphinoylimines employing cinchonidine and cinchonine as chiral ligands

The use of the `pseudoenantiomeric pair' of cinchonine and cinchonidine as ligands for the addition of diethylzinc to N-diphenylphosphinoylimines has been investigated. With 1 equiv of cinchonidine as ligand, a series of chiral amines was prepared in good yield and enantiomeric excesses of up to 94%. The use of 2.0 equiv of methanol as an achiral additive was found significantly to improve the selectivity of the addition when using 0.2 equiv of ligand, yielding ee's close to those obtained with a stoichiometric amount of ligand.

Tetranuclear tungsten cyclooctatetraenyl alkoxides [W 2COT(OR) 4] 2, where R=Me, Et and Pr

Two equivalents of W 2COT(NMe 2) 4 react with eight equivalents of methanol, ethanol, or n-propanol to form the corresponding tetranuclear alkoxide clusters: [W 2COT(OR) 4] 2 where R=Me, Et, or Pr. Single-crystal X-ray diffraction studies on the ethoxide and propoxide compounds reveal centrosymmetric molecules containing two [W 2(μ-η 5,η 5-COT)(μ-OR)(OR) 2] fragments. Each fragment has a W–W bond length of ca. 2.39 Å and is connected to the other by a pair of symmetrically-bridging alkoxides. These bridging alkoxides are not cleaved in the presence of σ-donors thf and pyridine, or π-acceptor 2-butyne. NMR data suggest that this structure is maintained in solution. Unlike in the related dinuclear alkoxides, W 2COT(OR) 4 [where R=CH 2Bu t , Pr i and Bu t ], the COT ligands are not fluxional at ambient temperature. The structural similarities between [W 2COT(OPr) 4] 2, W 2COT(OBu t ) 4, and W 4(H) 2(OPr i ) 14 are discussed.

Oxidation chemistry of uranium(III) complexes of Tpa: synthesis and structural studies of oxo, hydroxo, and alkoxo complexes of uranium(IV).

The crystal structure of the complex [U(tpa)(2)]I(3), 1 (tpa = tris[(2-pyridyl)methyl]amine), has been elucidated. The complex exists as only one enantiomer in the crystal leading to the chiral space group P2(1)2(1)2(1). The coordination geometry of the metal can be described as a distorted cube. Accidental oxidation of [U(tpa)(2)]I(3) led to the isolation of the unusual mononuclear bishydroxo complex of uranium(IV) [U(tpa)(2)(OH)(2)]I(2).3CH(3)CN, 2, which was structurally characterized. The controlled reaction of [U(tpa)(2)]I(3) with water resulted in the oxidation of the metal center and led to the formation of protonated tpa and of the trinuclear U(IV) oxo complex ([U(tpa)(mu-O)I](3)(mu(3)-I))I(2), 3. The solid state and solution structures of this trimer are reported. The pathway suggested for the formation of this complex is the oxidation of the [U(tpa)(2)]I(3) complex by H(2)O to form a U(IV) hydroxo complex which then decomposes, eliminating mono-protonated tpa. The comparison with the reported reaction with water of cyclopentadienyl derivatives points to a higher reactivity toward water reduction of the bis(tpa) complex with respect to the cyclopentadienyl derivatives. The reaction of U(III) with methanol in the presence of the supporting ligand tpa leads to formation of alkoxo complexes similarly to what is found for amide or cyclopentadienyl derivatives. The monomethoxide complex [U(tpa)I(3)(OMe)], 4, has been prepared in good yield by alcoholysis of the U(III) mono(tpa) complex. The crystal structure of this complex has been determined. The reaction of [U(tpa)(2)]I(3) with 2 equiv of methanol in acetonitrile allows the isolation of the bismethoxo complex of U(IV) [U(tpa)I(2)(OMe)(2)], 5, in 35-47% yield, which has been fully characterized. To account for the oxidation of U(III) to U(IV) the suggested mechanism assumes that hydrogen is evolved in both reactions.

Improvement in lipase-catalyzed synthesis of fatty acid methyl esters from sunflower oil

Biodiesel as alkyl esters derived from vegetable oils has considerable advantages in terms of environmental protection. In the present work, methyl esters were produced from sunflower oil by lipase-catalyzed reactions. The effect of organic solvent on alcoholysis rate was investigated and highest conversion (80%) was found in n-hexane and petroleum ether. Among several microbial lipases tested for alcoholysis activity in a solvent-free system, the best conversion (>90%) was found with lipase from Pseudomonas fluorescens (Amano AK) at the highest molar equivalent of oil:methanol (1:4.5). To reduce inactivation of commercial immobilized lipases by methanol, a three-step protocol consisting of the stepwise addition of 1 M equivalent of methanol at 5 h intervals, was developed. Also with immobilized lipase from Rhizomucor miehei (Lipozyme RM IM) high conversion (>80%) was possible. Moreover, the transesterification could be conducted for at least 120 h during five batch runs without significant loss of activity.

Reactivity of the 5-Hydroacenaphthylene Anion towards Electrophiles

The dianion of acenaphthylene can be converted into the 5-hydroanion by protonation with one equivalent of methanol. Subsequent reaction with electrophiles such as allyl bromide and propargyl bromide occurs selectively at position 1, resulting in the formation of the novel 1-allylacenaphthene and 1-propargylacenaphthene. In addition to what was observed in the case of methyl iodide, the hitherto unknown 1,1-dialkylated acenaphthene derivatives are formed as minor products; probably the lower reactivity of the unsaturated bromides is responsible for this side reaction. From the products of the reactions with 3,3-dimethylallyl bromide and (bromomethyl)cyclopropane the mechanism was found to be SN2. Reaction of the hydroanion with benzyl bromide takes place at position 1 as well as at position 2a. The reactivity of carbon 2a towards the soft electrophile benzyl bromide is attributed to the high HOMO coefficient at this position.